The present invention relates to an air exchange system for use in multi-story buildings which, in particular, reduces the average floor to floor height required in multi-story buildings.
A typical steel frame multi-story office or residential or mixed use) building is built with a 12'6" to 13' floor to floor height. This allows for an 8'6" to 9' ceiling height measured from ceiling to finished floor (not the top of the access floor.) Approximately 4' is reserved for ceiling space and included therein, for example, are concrete/metal decks, steel framing, fireproofing, air distribution systems, lighting, sprinkler systems, and other ceiling construction. A large portion of this 4' space is needed for accommodating the air distribution system for air conditioning and/or heating the occupied space.
In addition to the ceiling space required between floors, many office buildings that are built today also require access flooring to be built throughout the occupied space in order to facilitate the installation and replacement of wiring which is required to operate and interact with computers, telephones, communication systems, typewriters, etc. A typical access floor for normal office use is 6". Many special applications such as computer rooms, trading floors, etc. require floors as high as 24".
When a 6" access flooring is included as a tenant amenity, the available ceiling height decreases to approximately 8' to 8'6". In order to achieve a 8'6" ceiling with a raised floor and a 12'6" floor to floor height, more design and construction effort is required to make the ceiling less deep. Consequently, the construction is more costly due to the increase in materials, such as increased curtainwall, increased material for longer elevator travel and more structural steel. The curtainwall, for example, of a new building could be as high as $75.00/sq. ft. or $38.00 a foot of perimeter per floor of building to raise the floor-to-floor height by 6".
In a typical 50 story office building, this cost would normally fall in the range of $1,500,000 or approximately $1.00/sq.ft. of floor area. In addition to the increased cost, many zoning laws restrict building height such that if the floor to floor height is increased the developer will lose available floor area.
In one attempted solution to this problem, an access floor manufacturer has developed a system which distributes air under the floor. In this system, air is pumped under low pressure under the floor using a typical air conditioning ducts. The air in the ducts enters the office areas through grilles cut in the access floor. These grilles are spaced according to the tenant's individual space plan. Since the air is under low pressure, a fan located in the grill is used to suck the air out of the floor space and into the office space. The fan is thermostatically controlled to control the space temperature. The air conditioning unit is located within the core of the building near the elevators. Air from the unit must then cross under the corridors usually placed around the core by space planners. However, the corridor area is also used to run the wiring systems and is therefore most likely to require service. Servicing this area requires removal of the panels located along the floor and usually near the source of the incoming air. Removal of the panels causes the remaining floor to be deprived of air conditioning or heating for extended periods of time. Furthermore, improper replacement of the panels will result in an air leak. For these reasons, this system has had limited success.
As noted by the foregoing, the prior art has failed to provide an air conditioning and distributing system for use in a multi-story building which minimizes the floor to floor height needed to construct the building while providing available ceiling height of at least 8', for example, in the occupied user space.